Research Project V uses engaging adaptive computer-assisted reading programs to study questions about Response to Instruction (RTI) with children at risk for or with reading difficulties. Previous CLDRC research by Wise and colleagues demonstrated that talking computer programs can provide individualized, effective reading intervention for children in 2nd- 5th grades in schools. Recent advances in computer speech, voice recognition, animation, and design have led to improved related programs. Foundations to Literacy (FtL), by Wise, Cole and colleagues, is an integrated system of foundational exercises and interactive books which is used also with younger children. It includes frequent automatic RTI assessment, adjustment of program content and assured fidelity of treatment. The system closely monitors children's performance with engaging activities that improve word reading, spelling, writing, and accurate fluent text reading with comprehension, while an animated Virtual Tutor provides hints and support. FtL will be deployed in three studies of RTI: two in schools and one in the homes of twins with reading disabilities assessed in other projects. One school study involves kindergarten children at risk for reading problems. The second focuses on children with or at risk for reading difficulties in 1st-4th grades. Twins from Projects l-lll and a related longitudinal study have extensive assessment data, and will participate in an RTI study in their homes. Older struggling readers have a particularly difficult time achieving fluent grade-level reading with comprehension;many need much more extensive time reading accurately than schools can provide. Computers in homes with adaptive supported programs may help solve this problem for older children, and for children whose schools do not use the most appropriate intervention methods. Project V will thus provide valuable evidence about RTI: about how initial assessments interact with performance measures of rate or outcome in different reading domains to predict eventual outcomes from the programs. The project will add unique insights about individual differences and the molecular-genetic basis of RTI, since DMA samples have been provided by twins and will be requested from children in the school studies for Project IV to analyze. Finally, Project V explores benefits of intensively modified computer-assisted intervention programs in extended training beyond 1 year for poor responders.